Classification of Pressure Reducing Valves

1. Direct Acting Pressure Reducing Valve

The simplest Pressure Reducing Valve, the direct acting Pressure Reducing Valve, with a flat diaphragm or a bellows. Since it is an independent structure, there is no need to install an external sensing wire at the downstream end. It is the smallest in volume and the most economical among the three Pressure Reducing Valves, and is specifically designed for medium and low flow rates. The accuracy of the direct acting Pressure Reducing Valve is typically +/- 10% of the downstream setpoint.

2.Piston-type Pressure Reducing Valve

This type of Pressure Reducing Valve integrates two valves - the pilot valve and the main valve. The design of the pilot valve is similar to that of the direct acting Pressure Reducing Valve. The exhaust pressure from the pilot valve acts on the piston, causing it to open the main valve. If the main valve is too large to be opened directly, this design will use the inlet pressure to open the main valve. Therefore, compared to the direct acting Pressure Reducing Valve, this type of Pressure Reducing Valve has higher capacity and accuracy (+/-5%) under the same pipe size. Similar to the direct acting Pressure Reducing Valve, the Pressure Reducing Valve senses the pressure internally and does not require an external sensing wire.

3. Membrane-type Pressure Reducing Valve

In this type of Pressure Reducing Valve, two diaphragms replace the piston found in the internal-guide Pressure Reducing Valve. The enlarged diaphragm area enables the opening of a larger main valve, and with the same pipe size, its capacity is greater than that of the internal-guide piston Pressure Reducing Valve. Additionally, the diaphragm is more sensitive to pressure changes, with an accuracy of +/-1%. The higher accuracy is due to the positioning of the downstream sensing wire (outside the valve), which has less gas or liquid turbulence at its location. This Pressure Reducing Valve is very flexible and can be equipped with different types of pilot valves (such as pressure valves, temperature valves, air loading valves, electromagnetic valves, or several valves in combination).